Thermo-actuator



Oct. 22, 1957 v .1. F. SCHERER 2,810,290

Y THERMO-ACTUATOR Filed April 8, 1954 5 Sheets-Sheet l INVENTO JAMES E SCHE R 1 BY 7 DES JARDINS, ROBINSON 8. KEIS ER HIS ATTORNEYS Oct. 22, 1957 J. F. SCHERER 2,810,290

THERMO-ACTUATOR Filed April 8, 1954 s Sheets-Sheet a INVENTOR. I60 JAMES F. SCHERER BY DES JARDINS, ROBINSON 8. KEISER H IS ATTORNEYS United States Patent 'QQfiFiCe 2,810,290 Patented Oct. 22, 1957 THERMO-ACTUATOR James F. Scherer, Terrace Park, Ohio Application April 8, 1954, Serial No. 421325 14 Claims. (Cl. 73-3683) This invention relates to temperature control devices, and particularly to thermo-actuators of the type which produce a thrust of considerable magnitude within a narrow temperature range for enabling positive and accurate control to be eifected thereby.

Temperature controlling devices have long been known in which the change in volume experienced by certain materials over a limited temperature range has been used to produce a desired control effect. The materials commonly used in these devices for effecting the desired control are waxes or combinations of waxes having a high rate of expansion while passing from a solid state to a liquid state. It is also known that the inclusion of copper fines or aluminum fines in the heat expansible material accelerates the transfer of heat through the material and thereby increases the sensitivity of the device to sudden temperature changes. In all of the prior devices of this character with which I am familiar, the temperature responsive material is contained in a metal cup covered by a resilient diaphragm which is relied upon to seal the material in the cup and also to transmit the expansion of the material to a piston connected with the control apparatus. A return spring is customarily provided for returning the piston and diaphragm to their normal positions upon cooling and contraction of the material in the cup. In these prior devices it has been found very difiicult to seal the material within the cup so as to prevent its escape therefrom, and also to prevent the fluid, in which the device is immersed, from gaining entrance into the cup. It is with a view to eliminating this problem of sealing off the heat expansible material from the fluid whose temperature is being controlled, as well as for the purpose of providing an improved and more reliable form of thermo-actuator that I have devised the constructions shown and described herein.

Accordingly, it is an object of my invention to provide an improved form of thermo-actuator which is more reliable and longer-lived than presently known devices of this character.

Another object of my invention is to provide a thermoactuator incorporating improved means for positively sealing off the heat expansible medium from the surrounding fluid.

Another object of my invention is to provide a temperature controlled actuator in which the heat expansible material is embraced within a self-contained, sealed capsule.

Another object of my invention is to provide a temperature responsive actuator in which the reciprocable piston is located off-center with respect to the center of the capsule thereby effecting rotation of the capsule in response to repeated cyclical operation of the piston.

Another object of my invention is to provide a heat responsive actuator in which the heat expansi'ble medium is contained within a capsule provided with a heat transfer pin extending from the exterior of the capsule into the interior thereof. Y

With these and other objects inview which .will become apparent from the following description, the invention includes certain novel features of construction and combinations of parts, the essential elements of which are set forth in the appended claims, and several preferred forms or embodiments of which will hereinafter be described with reference to the drawings which accompany and form a part of this specification.

In the drawings:

"Fig. 1 is a cross-sectional view illustrating one embodiment of my invention.

Fig. 2 is a cross-sectional view showing another form of my invention.

Fig. 3 is a plan view in cross-section showing still a further form of my invention.

Fig. 4 is a cross-sectional view taken along the line 44 in Fig. 3.

Fig. 5 is a cross-sectional elevation of the device shown in Fig. 3.

Fig. 6 is a cross-sectional elevation of another form of my invention.

Fig. 7 is a cross-sectional view taken along the line 77 in Fig. 6.

Fig. 8 is a plan view in cross section of the device shown in Fig. 6.

Fig. 9 is an enlarged view of the sealing means shown in Fig. 7.

in the accompanying drawings I have illustrated several diferent forms or modifications of my invention all of which incorporate a self-contained, sealed capsule embracing the heat expansible material which generates the thrust produced by the device when the operative range of temperatures is reached. in each case, the heat expansible material contained in the capsule is characterized by its rapid change in volume over a narrow temperature range so as to provide for positive actuation of the device to be controlled at a predetermined temperature. A suitable material for use within the capsules is described in U. S. Patent No. 2,259,846, granted on October 21, 19-41, to Sergius Vernet et al. for Temperature Responsive Element. in the construction shown in Fig. 2 of the drawings, the temperature responsive material 10 is contained within a sealed capsule 12 formed of resilient material such as natural or artificial rubber or synthetic resins which will withstand the repeated expansion and contraction of the material it) and which will, by virtue of the restorative force acting on the piston, tend to return it to its normal shape as shown in Fig. 2. The heat responsive material in may be injected into the capsule 12 through a hole provided in the side wall thereof which may thereafter be sealed shut by any of the various expedients well known in the art. The capsule 12 is adapted to be received in a chamber 14 formed in a housing 16 consisting of a body is and a cap 26. The body and cap should be constructed of a material having high heat conductivity such as brass, copper, aluminum, etc., so that the variations in heat to which the device is subjected may readily pass through the housing and into the capsule. While the shape or" the chamber 1 5 may be either cylindrical or spherical, in the present instance it is spherical in shape and the capsule 12, in this particular case, takes the form of a sphere or ball, the outside diameter of which is substantially equal to the diameter of the chamber 14. The capsule will, therefore, completely fill the chamber at temperatures below the operating range in which the heat expansible material 10 is in its unexpanded condition. Hence, any significant expansion of the material 28 will be transmitted to a piston 22 which is received for sliding movement in a bore 24 provided in the cap 2%). The piston is provided with a stem 26 which is slidably received in a bore 28 extending through the end of the cap. In the embodiment shown, a pin 30,

which is equal in diameter to the stem 26, is.also received within 'the bore 28 and transmits motion from the piston to the apparatus which is to be controlled by the thermoactuator device. The inner end 32 of the piston 22 is shaped to conform with the contour of the wall of the dhamber 14 so as to provide, in effect, an extension of the chamber wall'when the pistonis in its normal, unaotuated position as shown in Fig. 2. If desired, the piston 22 may be provided with an expansion recess 34 for absorbing'any abnormal expansion of the'm'ateiial 10. Thus, if the material in the capsule continues, through excessive heating, to expand after the piston has reached the end of the bore 24,'the capsule may enter the recess 34 upon continued expansion of the material and prevent any damage to the thermo actuato'rdevice.

The thermo-actuator device shown in Fig. 2 isactually much smaller than indicated by the present drawing, it being shownon an enlarged scale herein to clearly illustrate the details of the various constructional features thereof. The device is assembled by placing the capsule 12, which forms a self-contained, sealing unit, in the hemispherical recess formed in the body 18 after which the cap 28 is inserted in the body with its flanged inner end 36 seated against the bottom of the recess provided therefor in the body 18. The lip 38 is then spun over as indicated in Fig. 2 to securely fasten the body and cap together to constitute a unitary housing 16 with the capsule 12 embraced within the cavity 14.

Although not shown herein, a return spring, which may form part of the apparatus controlled by the thermoactuator device, is utilized to return the piston 22 to its normal position as shown in Fig. 2 upon contraction of the material 10 after the temperature has returned to normal. The material forming the wall of the capsule 12 will, of course, due to its elasticity, tend to return to the position shown upon contraction of the heat expansible material 16, but the contractive force thus exerted may not be sufficient to completely return the capsule to its normalshape without the assistance of external restoring means. In this connection it is tobe realized that the wall of the capsule should he kept as thin as possible consistent with the strengthrequirements thereof so as to not interfere with the transmission of heat from the housing 16 into the heat expansible material It? contained within the capsule.

A more rapid transfer of heat from the exterior of the device into the heat expansive material contained therein may be achieved by means of the construction in Fig. 1. As herein shown, a body of heat expansible material 40 is embraced withina capsule 42 formed of a wax, or a like material, such as certain types of polyethylene glycol 3r other materials which, though rigid and solid at normal temperatures, are adapted to melt and remain in the liquid state within the operating temperature range of the thermo-actuator device, thereby allowing the material formerly enclosed therein to actuate the piston of the thermo-actuator device. The liquid into which the wall of the capsule is transformed upon an elevation in temperature should be compatible with the heat expansible material 40 so that no undesirable effects will be produced on the latter material by the melting of the capsule sheath. Here again the capsule is in the form of a self-contained unit which may be readily handled at normal or slightly subnormal temperatures and which may be conveniently inserted in the device in the course of assembly the same as the capsule 12 in the form of device shown in Fig. 2. In the case of the gelatin type capsule, it will, of course, become. necessary to seal the deviceagainst the escape of liquid or gas from the chamber44 within whiehthe capsule 42 is received. Toward this end, the piston 46 is provided with circumferential groovesreceiving O-rings '48 formed of resilient material and being of conventional construction. An additional O-ring 49 is-seated in an. annular groove provided in the bottom of the bore stlprovidedin the cap 52 Within which the piston is slidable. The O-ring 49, upon full expansion of the capsule, will engage against the outer face 54 of the piston and further guard against the ingress or egress of liquid or gas from the outside of the device into the chamber 44, or vice versa. The joint between the cap 52 and body 56 may be sealed by a large O-ring 58 received within an annular groove provided in the bottom of the recess provided in the body. Hence, when the cap 52 is inserted in the body and the lip 59 spun over, the ring 58 will be tightly compressed and form a tight seal to guard chaniber44 againstthe ingress or egress of either liquid or gas. In all other respects the thermo-actuator device shown in Fig. 1 is like the device shown in Fig. 2.

In the Fig. 2 embodiment of the invention, the frequent and continued flexing of the capsule wall around the edge of the piston 22 stresses the capsule at this point and may eventually cause a rupture or break in the material forming the wall thereof. This condition maybe alleviated by using the type of construction embodied in the merino-actuator device shown in Figs. 3, 4 and 5 of the drawings. In this form or device, the capsule is made cylindrical in form and is adapted to rotate about the axis of thecylinder during repeated operation of the actuator. As shown herein, a cylindrically shaped capsule 60 containing a body of heat expansible material 62 is received in a cylindrical chamber 64 provided in a body 66. The body 66 is itself in the shape of a cylinder and is re ceived within a cylindrical shell 68. The body is held in place withinthe shell by means of a cap 70 provided with an axial bore 72 which receives and guides the stem 74 of a piston 76 which is rectangular in cross-section and which -is guided in a hole 77 in the body 66. Also slidably mounted in the bore 72 is a thrust pin 78 which contacts the end of the stem 74 and communicates the thrust produced thereby to the apparatus to be controlled by the thermo-actuator device. The cap 70 is held in place on the shell 68 by a spun-over lip 80 formed on the open end of the shell. As shown in Fig. 4, the capsule 60 is placed inthe cylindrical recess provided in the body member66 after which a plug 82 is placed over the capsule in'therecess. The body member may then be slidinto the shell 68 which will retain the plug 82 in place within the recess in the member :66.

The capsule '60 is preferably formed of moulded rubber or other suitable resilient material and is provided with an open neck 84 on one side thereof as shown in Fig. 4. The neck is'fitted with a two-piece metal bushing 86 the two elements of which are press fitted or threaded together with-a reentrant flange 88 formed on the neck 84 seized therebetwee'n to form a tight seal at this point. The .bushing is provided with a filling hole 90 which may be closed by a taper plug 92 after the heatexpansive material has been injected into the capsule. The circumferential faces'94 and 96 on the bushing 86 cooperate with mating surfaces provided in the plug 82 and are freely rotatable with respect thereto. Hence, the bushing 86.providesa trunnion forthe capsule and allows it to rotate about its longitudinal axis within the chamber 64; The exterior surface of the capsule may be coated with a suitable'lubricant so as to facilitate turning of the capsule in the chamber.

As will be observedfrorn the cross-sectional plan view o f the device shown in Fig. 3, the inner end of the piston'76 is offset with respect to the central axis of the capsule and also with respect to the cylindrical stem 74 of the. piston. The inner face 98 of the piston is contoured .to eonform to the shape of the wall of the chamb63 64. Accordingly, when the piston is in its inner or normalposition, a smooth, unbroken cylindrical wall is presented :to the capsule 60. However, upon expansion of the material62 within thecapsule, the latter will press against-the-e1id of the piston and force the same outwar d asindicated in Fig. 3. Inso doing, a protuberance 100 is formed on the capsule as it follows the retreating end f the piston into the rectangular hole 77. As the capsule expands into the recess afforded by the hole 77, the resilient material of the capsule wall lying beyond the corner 106 flows more readily into the recess than the portion of the capsule lying beyond the corner 108. In other words, the sharp corner 108 serves as an anchor point and prevents the material lying beyond that corner from moving around the corner and into the hole 77 during expansion of the capsule. After the heat expansive material 62 within the capsule again cools and contracts, the capsule will return to its normal shape. In so doing, the material of the capsule wall in the protuberance 100 will tend to move around the corner 108 to relieve the tension in the capsule wall lying beyond this corner. Hence, there will be a creeping action of the capsule in a clockwise direction as viewed in Fig. 3 upon repeated expansion and contraction of the capsule. The wall of the capsule is therefore continuously shifted past the corners 106 and 108 so that the same portions thereof are not always subjected to repeated stressing at these points. This relieves much of the fatigue on the capsule wall and also has the beneficial effect of continuously working all of the material in the wall which, in the case of a substance such as rubber, is highly beneficial and keeps it live and elastic.

In the form of device shown in Figs. 3 to 5, inclusive, an expansion plug 11%] is provided in the end of the device opposite the piston for taking up any abnormal expansion of the material 62. As best shown in Fig. 3, the plug 110 is slidable within a bore provided in the body 66 and is provided with an annular flange 112 which is slidably received within a bore 114 provided in the end bell 115 of the shell. The bore 114 is closed by a screw cap 116 having a tenon 118 which extends into a bore provided in the plug 110 and serves as a guide for the plug. A compression spring 120 confined between the plug 110 and the screw cap 116 applies sufiicient pressure on the plug to maintain it in the position shown in Fig. 3 in which an inner face 122 is flush with the surface of the chamber 64 and provides a continuation of the cylindrical contour thereof. However, should the material 62 continue to expand due to excessive heating after the piston 76 has been forced to its limit of movement as shown in Fig. 3, the spring 120 will then yield and permit the plug 110 to be forced outwardly and prevent destructive strains being generated within the thermo-actuator device. 1

In the case of the device shown in Figs. 3 to 5, inclu'sive, as in those shown in Figs. 1 and 2, the scale is greatly enlarged for the purpose of clearly illustrating the interior construction of the devices.

To promote rapid heat transfer from the outside surface of the thermo-actuator device to the heat expansible material contained within the interior thereof, and also to increase the net expansion of the capsule unit, I have devised the construction shown in Figs. 6, 7 and 8. In this form of the device, heat expansible material 130 is contained in a capsule 132 which may be formed of rubher or other suitable resilient and elastic material. As shown in the drawings, this capsule is in the form of a cylinder having an enlarged central portion 134 (Fig. 7) and reduced end portions 136 and 138 which are each provided with cylindrical axial openings 137 and 139, respectively. The opening 137 communicates with the interior of the capsule and is adapted to receive a heat transfer pin 14% having an enlarged head 141 formed with a spherical crown 142. The pin 1% is provided with a sealing groove 144 into which the wall material of the capsule 132 is squeezed by a lock ring 146. This ring is preferablyrformed of a rather stiff, unyielding material such as rubber havinga hardness of 80 to 9t) durometer. It is to be realized, of course, that a syntheticmaterial having suitable hardness and elasticity characteristics might be used in place of rubber and that even a ring formed of coiled metal wire might be used in lieu thereof. The elasticity of the ring 146 is such that it can be stretched sufliciently to go over the head 141 of the pin and be rolled along the cylindrical end portion 136 of the capsule 132 until it has reached the position shown in Fig. 7. The inner end of the pin 14% extends into close proximity to the end wall 148 of the capsule and presents a large heat conductive surface to the heat expansible material 1311 contained within the capsule. A pin 150, similar to the pin 140, extends into the hole 139 and is provided with a head 151, the crown of which may, like the crown 142 of the pin 140, be made spherical in shape so as to have line contact with the cylindrical inner face of the housing or shell of the device. However, if desired, the crowns of both pins may be made cylindrical to conform to the surface on the inside of the shell and provide surface contact therewith over a wide area. The pin is provided with a sealing groove 152 into which the rubber material of the capsule is squeezed by a lock ring 153. Surrounding the tenons 136 and 138 on the capsule are spacer sleeves 154 and 156, respectively, which have a diameter equal to that of the enlarged portion 134 of the capsule.

Each spacer sleeve is provided at its inner end with a counterbore for receiving the lock rings 146 and 153. As best shown in Fig. 9, this counterbore includes an inclined face 147 and a cylindrical face 149. The diameter of the face 149 is preferably slightly less than the outside diameter of the lock ring 146 when this ring is in place on the capsule as shown in Fig. 9. The ring will thereby be compressed and cause the resilient capsule material to be tightly squeezed against the pin 140 and into the sealing groove 144. The inclination of the face 147 is such that a line drawn normal to its surface and passing through the center of the lock ring 146, such as the line 145, will pass approximately through the center of the sealing groove 144 formed in the pin. The angle of inclination of the line 145 with respect to the interface between the pin and the capsule wall, which is indicated by the letter x in Fig. 9, is of the order of fromSO to 70. In other Words, the angle of inclination y of the face 147 with respect to the surface of the pin lies within the range of from 40 to 20.

The above-described arrangement of the lock ring 146, sealing groove 144, and counterbore comprised of faces 147 and 149, provides an unusually effective seal between the capsule and the surface of the heat transfer pin. By virtue of the angular arrangement provided by the inclined face 147 and the location of the lock ring 146 with respect to the sealing groove 144 outward pressure created by expansion of the heat expansible material 130 within the capsule will have theeifect of forcing the lock ring outward thereby producing greater compression of the ring on the capsule material by virtue of the inclined face 147. Hence, the greater the pressure on seal, the greater the sealing force will become so as to positively prevent the escape of any fluid material from within the expansion chamber of the capsule.

It will be understood, of course, that the eflicient operation of my novel form of seal will be achieved even though the sealing groove 144 be shifted outwardly somewhat from its present position as shown in Fig. 9 though I prefer that the relation of the groove and the pressure face 147 be as previously shown and described.

The capsule 132 and sleeves 154 and 156 form a cylindrically shaped unit which is adapted to be received within a transverse cylindrical bore provided in a body 160. This bodyis in the form of a cylinder with its axis lying at right angles to the axis of the cylinder constituted by the capsule 132 and the sleeves 154 and 156. The body 160 is provided with a rectangular hole 162 in which the piston 164 is slidable. As shown in Fig. 6, the inner end of the piston is offset from its stem 166 so as to cause creeping action of the capsule around its central axis as the heat expansible material alternately expands and contracts. The body 160 is receivable within a cylindrical shell 168 and is held in place therein by a cap 170 which is secured to the shell by a spun-over lip 17 2. The cap is provided with a bearing 174 for supporting and guiding the stem 166 of the piston.

As shown in Fig. 7, the heat transfer pin '140.is situated with its head 141 in intimate contact with the shell .168. Accordingly, heat transmitted to the shell will pass into the .pin and thereby be conducted into the interior of the capsule where it will heat the expansible material 130. In a similar manner, pin 150 lies with its head 151 in contact with the shell 168 so that thispinalso conducts heat from the shell toward the interior of the capsule.

A further advantage accruing from the extension of the heat transfer pin 140 into the interior of the capsule is that the expansion of the pin upon heating will expand the capsule outwardly thereby offsetting, in part, the outward expansion of the walls of the body 160. In other words, the reduced expansive effect of the material 130 due to expansion of the container within which the capsule is housed will be partially oflfset by the expansion of the pin 150.

The thermo-actuator device shown in Figs. 6, 7 and 8 is, like the previous devices, shown on an enlarged scale so as to clearly illustrate the detailed'features of its construction.

While I have described my invention in connection with certain specific forms or embodiments thereof and have used, therefore, certain specific terms and language herein, it is to be understood that'the present disclosure is illustrative rather than restrictive and that changes and modifications may be resorted to without departing from the spirit or scope of the claims which follow.

Having thus described my invention, what I claim as new and usefuland desire to secure by United States Letters Patent, is:

l. A temperature responsive device comprising a housing, a chamber in said housing having a circumferential wall, a displaceable member in said housing having an end face forming a predetermined segment of the circumferential wall of said chamber and reciprocable transversely of the axis of said chamber, the path of movement 'of the center of saidpistonbeing otfset in a'circumferential direction with respect to the axis of said chamber, a sealed capsule free to rotate within said chamber, and an expansible material in said capsule adapted to undergo a substantial change in volume with a change in temperature thereof to thereby cause movement of said displaceable member and incremental rotation of said capsule.

2. The device of claim 1 wherein said capsule has a wall formed of a resilient material.

3. The device of claim 2 wherein said capsule normally fills said chamber, and including means for absorbing abnormal expansion of said capsule.

4. A temperature responsive device comprising a housing having a body member anda cap member securely atfixed thereto, said members being shaped to form a completely=enclosed chamber within thehousing having a circumferential wall, a displaceable member in said housing having an end face forming a predetermined seg-v ment of the circumferential wall of said chamber and reciprocable transversely of the axis of said chamber, the path of movement of the center of said piston being offset in a circumferentialdirection with-respect to the axis of said chamber, a sealed capsule free to rotate within said chamber, and an expansible material in said capsule adapted to undergo a substantial change in volumewith a change-in temperature thereof to therebycause movement of said displaceable member and incremental rotation of said capsule.

5. The device of claim 4 wherein said displaceable member comprises a piston mounted for sliding movement in said cap member.

6. A therrno-actuatordevice comprising a body, a cylindrical chamber in said: body,.a pistonmounted for slid,-

ing movement-in said body transversely :of the axis of said chamber withthe inner end of said piston forming part of :the circumferential wall of said chamber and with the path of movement of the center ofisaid piston offset ina circumferential direction with respect to the axis of said chamber, acapsule having a wall ofresilient material within said chamber, and a substancevwithin said capsule adapted to undergo a substantial change. in volume with a change in temperature to thereby cause movement of said piston and incremental rotation of said capsule.

7. The device of claim 6 wherein saidpiston is provided with a stern which is offset with respect to the inner end of said piston, the axis of said stem coinciding with a radius of said chamber.

8. The device of claim 6 including asecond piston mounted for sliding movement in said'body with the end of said piston forming part of the circumferential wall of said chamber, and means for preventing movement of said second piston under normal pressures exerted thereon by said capsule.

9. The device of claim 8 wherein said preventing means includes a compression spring.

10. The device of claim 6 wherein means is 'provided on said capsulefor enabling the same to pivot aboutthe axis of said cylindrical chamber.

11. The device of claim 10 wherein said last-recited means includes a trunnion formed on said capsule.

12. A temperature responsive device comprising a housing having a cylindrical recess formed therein, a cylindrical body adapted to fit in said recess, said body being providedwith a cylindrical chamber disposed transversely of said body and said recess, a capsule in said chamber, a heat expansible material in said capsule, and a piston mounted in said body for movement'parallel to the axis of said bodywith the innerend of said piston forming part of the wall of said chamber, whereby expansion of the material in said capsule will cause outward movement of said piston.

13. The device of claim 12 wherein the inner end of said piston is offset in a circumferential direction with respect to the axis of said chamber.

14. A heat expansible cartridge for a temperature control device comprising a hollow cylindrical capsule formed of resilient material, a neck on one end of said capsule having an opening thereinextending into the interior of said capsule and in the direction of the axis thereof, a heat transmission pin passing through the opening in said neck and having an annular groove therein, means for clamping 'said neck around said .pinto deform the resilient material of the neck into said. groove to form a pressuretight seal therewith, a temperature responsive material in said capsule for expanding the same upon the transmission of heat to said material, and a second heat transfer pin received within a blind hole provided in the other end of said capsule.

References Cited in the file of this patent UNITED STATES PATENTS 214,122 Gary Apr. 8, 1879 251,355 Gibbs Dec.27, 1881 406,138 Hobson July 2, 1889 1,082,212 Pollard Dec. 23, 1913 1,484,816. Derby Feb. 26, 1924 1,521,985 Bastian Jan 6, 1925 2,133,860 Hill Oct. 18, 1938 2,208,149 Vernet July .16, 1940 2,593,238 Albright Apr. 15, 1952 FOREIGN PATENTS 345,050 France Sept. 28, 1904 1,019 Great Britain 1905 718,239 France Nov. 4, 1931 167,547 Switzerland May 16, 1934 

